Voltage regulator and power supply

ABSTRACT

A voltage regulator and a power supply are provided. The voltage regulator includes an operational amplifier and an offset voltage control module. The operational amplifier includes an input terminal and an output terminal, and is configured to generate an output voltage to be output from the output terminal based on a reference voltage received from the input terminal. The offset voltage control module includes one stage of regulation branch or more stages of regulation branches connected in parallel, and is configured to control an offset voltage of the operational amplifier based on selection of the regulation branch to regulate the output voltage. Since sine each stage of regulation branch in the offset voltage control module is based on a transistor structure, as compared with the voltage dividing resistor in the related art, the transistor has lower power consumption, and thus power consumption of the voltage regulator is lowered.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of international applicationNo. PCT/CN2017/113306, filed on Nov. 28, 2017, which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present disclosure relate to the technical field ofpower supply, and in particular, relate to a voltage regulator and apower supply.

BACKGROUND

A voltage regulator is generally used in an electronic system to ensurethat power supply supplies power stably in the electronic system and anoutput voltage of the power supply may be regulated. FIG. 1 illustratesa basic structure of a conventional voltage regulator. In FIG. 1, thevoltage regulator includes an operational amplifier, a regulationtransistor, a voltage dividing resistor R1 and a voltage dividingresistor R2. V_(IN) is an input voltage of the voltage regulator,V_(OUT) is an output voltage of the voltage regulator, and V_(REF) is areference voltage generated by a bandgap reference generation circuit.An operating process of the voltage regulator may be briefly summarizedas follows: a reference voltage V_(REF) is input to an inverting inputterminal of the operational amplifier, and an output voltage V_(OUT)subjected to sampling by the voltage dividing resistors R1 and R2 isinput to a non-inverting input terminal, and the output voltage V_(OUT)of the operational amplifier is connected to the regulation transistor(that is, the pass transistor in FIG. 1). The regulation transistor isconfigured to stabilize the output voltage V_(OUT) to achieve stablepower supply. In addition, the output voltage V_(OUT) is then regulatedby regulating a ratio of the voltage dividing resistor R1 to the voltagedividing resistor R2.

When the electronic system is in a standby state, the voltage regulatorstill needs to supply the output voltage V_(OUT) to ensure normaloperation of a part of modules in the electronic system. However, whenthe electronic system is in the standby state, a load current output bythe voltage regulator is small, whereas the voltage regulator may havehigh power consumption due to presence of the voltage dividing resistorsR1 and R2.

SUMMARY

Embodiments of the present disclosure are intended to provide a voltageregulator and a power supply, to at least solve the above technicalproblem in the related art.

To achieve the above objectives, embodiments of the present disclosureprovide a voltage regulator. The voltage regulator includes: anoperational amplifier and an offset voltage control module.

The operational amplifier includes an input terminal and an outputterminal, and the operational amplifier is configured to generate anoutput voltage to be output from the output terminal based on areference voltage received from the input terminal.

The offset voltage control module includes one stage of regulationbranch or more stages of regulation branches connected in parallel, andthe offset voltage control module is configured to control an offsetvoltage of the operational amplifier based on selection of theregulation branch to regulate the output voltage.

To achieve the above objectives, embodiments of the present disclosurefurther provide a power supply. The power supply includes the abovedescribed voltage regulator.

Embodiments of the present disclosure provide a voltage regulator and apower supply. The voltage regulator includes an operational amplifierand an offset voltage control module. The operational amplifier includesan input terminal and an output terminal, and is configured to generatean output voltage to be output from the output terminal based on areference voltage received from the input terminal. The offset voltagecontrol module includes one stage of regulation branch or more stages ofregulation branches connected in parallel, and is configured to controlan offset voltage of the operational amplifier based on selection of theregulation branch to regulate the output voltage. Since each stage ofregulation branch in the offset voltage control module is based on atransistor structure, as compared with the voltage dividing resistor inthe related art, the transistor has lower power consumption, and thuspower consumption of the voltage regulator is lowered.

BRIEF DESCRIPTION OF THE DRAWINGS

For clearer description of the technical solutions in embodiments of thepresent disclosure or in the related art, hereinafter, drawings that areto be referred for description of the embodiments or the related art arebriefly described. Apparently, the drawings described hereinafter merelyillustrate some embodiments of the present disclosure. Persons ofordinary skill in the art may also derive other drawings based on thedrawings described herein without any creative effort.

FIG. 1 is a schematic basic structural diagram of a voltage regulator inthe related art;

FIG. 2 is a schematic structural diagram of a voltage regulatoraccording to an embodiment of the present disclosure;

FIG. 3 is a schematic structural diagram of an operational amplifieraccording to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of another operationalamplifier according to an embodiment of the present disclosure;

FIG. 5 is a schematic structural diagram of an offset voltage controlmodule according to an embodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of a conventional bandgapreference generation circuit according to an embodiment of the presentdisclosure;

FIG. 7 is a schematic structural diagram of a PTAT unit-based andBJT-based bandgap reference generation circuit having a complementarystructure according to an embodiment of the present disclosure; and

FIG. 8 is a schematic structural diagram of PTAT unit according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

Practice of the present disclosure is described in detail with referenceto drawings and specific embodiments, such that the practice ofaddressing the technical problem using the technical means according tothe present disclosure and achieving the technical effects may be betterunderstood and conducted.

FIG. 2 is a schematic structural diagram of a voltage regulatoraccording to an embodiment of the present disclosure. In thisembodiment, FIG. 2 illustrates a structural principle of the voltageregulator. Exemplary structures of various units in the voltageregulator may be referenced to disclosure in the embodimentshereinafter.

As illustrated in FIG. 2, the voltage regulator includes an operationalamplifier 21 and an offset voltage control module 22.

The operational amplifier 21 includes an input terminal and an outputterminal, and the operational amplifier is configured to generate anoutput voltage V_(OUT) to be output from the output terminal based on areference voltage V_(REF) received from the input terminal.

In this embodiment, when an input voltage at the input terminal is 0 V,the output voltage V_(OUT) is −V_(OS). V_(OS) is an offset voltageV_(OS) of the operational amplifier. In an ideal state, when the inputvoltage at the input terminal of the operational amplifier is 0 V, theoutput voltage V_(OUT) is also 0 V. That is, the offset voltage V_(OS)is 0 V. However, in practical disclosure, the input voltage of theoperational amplifier does not match the output voltage thereof. Thatis, when the input voltage at the input terminal is 0 V, the outputvoltage V_(OUT) is not 0 V. That is, the offset voltage V_(OS) is not 0V.

In this embodiment, an exemplary structure of the operational amplifiermay be referenced to FIG. 3 or FIG. 4.

The offset voltage control module 22 includes one stage of regulationbranch or more stages of regulation branches connected in parallel, andthe offset voltage control module 22 is configured to control an offsetvoltage V_(OS) of the operational amplifier based on selection of theregulation branch to regulate the output voltage V_(OUT).

In the related art, the offset voltage V_(OS) may be equivalent to avoltage source loaded at the input terminal of the operationalamplifier. Therefore, by regulating the offset voltage V_(OS), it may beensured that the output voltage V_(OUT) is also 0 V when the inputvoltage of the operational amplifier is 0 V. It is thus apparent thatthe output voltage of the operational amplifier is affected by theoffset voltage. Therefore, in this embodiment, the output voltageV_(OUT) of the operational amplifier may be controlled by controllingthe offset voltage V_(OS).

In this embodiment, by using the one stage of regulation branch or morestages of regulation branches connected in parallel, the offset voltageV_(OS) is regulated under cooperation actions of the transistors in theregulation branches.

Each regulation branch may specifically include a plurality oftransistors. The types of the transistors and connections between thetransistors may be determined based on the circuit structure of theoperational amplifier and the device that is connected to the offsetvoltage control module in the operational amplifier. Differentregulation branches may have different circuit structures.

For example, when two values, A V or B V, of the output voltage V_(OUT)are needed, the offset voltage is also only C V or D V; when V_(OS)=C V,the output voltage V_(OUT) is A V; and when V_(OS)=D V, the outputvoltage V_(OUT) is B V. In this case, the above demand may be satisfiedonly by using one stage of regulation branch, and the offset voltagecontrol module 22 may only include one stage of transistor-basedregulation branch.

However, when more than two values of the output voltage V_(OUT) areneeded, more stages of regulation branches connected in parallel aredesired for cooperation. In this case, the offset voltage control module22 includes more stages of transistor-based regulation branchesconnected in parallel.

In addition, in this embodiment, more stages of regulation branches areconnected in parallel because when the more stages of regulationbranches are connected in parallel, the regulation branches may berandomly selected for use, and changes of one regulation branch may notaffect the other regulation branches. In this way, equivalenttransistors having different parameters may thus be formed, such thatthe offset voltage V_(OS) may be regulated.

In this embodiment, an exemplary structural diagram of the offsetvoltage control module may be referenced to FIG. 5 hereinafter.

In this embodiment, since each stage of regulation branch in the offsetvoltage control module is based on a transistor structure, as comparedwith the voltage dividing resistor in the related art, the transistorhas lower power consumption, and thus power consumption of the voltageregulator is lowered.

In addition, use of the voltage dividing resistor in the related artresults in a large occupied area. However, with respect to thetransistor-based regulation branch in this embodiment, since thetransistor occupies only a small area, disclosure of the transistorreduces the area desired by the voltage regulator.

FIG. 3 is a schematic structural diagram of an operational amplifieraccording to an embodiment of the present disclosure. In thisembodiment, the operational amplifier may be specifically a buffer (BUF)amplifier. As illustrated in FIG. 3, the buffer amplifier includes: PMOStransistors MP1, MP2 and MP3, NMOS transistors MN1, MN2, MN3 and MN4,and a capacitor C1.

MP1 and MP2 share a common gate and a common drain, the sources of MP1and MP2 are electrically connected, and the drain is connected to adrive voltage VDD, a source of MP1 is connected to the gate thereof,such that a current mirror structure is formed.

MN1 and MN2 are differential input pair transistors of the bufferamplifier, a drain of MN1 is connected to a source of MP1, a drain ofMN2 is connected to a source of MP2, a source of MN1 and a source of MN2are both connected to a drain of MN3, a gate of MN3 is connected to abias voltage VBN such that MN3 operates, and a source of MN3 isconnected to the ground.

A gate of MN1 and a gate of MN2 are respectively used as an invertinginput terminal and a non-inverting input terminal of the bufferamplifier, and the drain of MN2 is used as an output terminal of adifferential unit.

The above MP1, MP2, MN1, MN2 and MN3, and the specific connectionstherebetween form a double input single output differential unit loadedon a PMOS current mirror.

The drain of MN2 is connected to the capacitor C1 and a gate of MP3respectively, a drain of MP3 is connected to the drive voltage VDD, asource of MP3 is connected to the other terminal of the capacitor C1 andconnected to the drain of MN3, and is used as an output terminal of thebuffer amplifier, a source of MN4 is connected to the ground, and a gateof MN4 is connected to the bias voltage VBN such that MN4 is conducted.

The above C1, MP3 and MN4, and the specific connections therebetweenform an output unit of the buffer amplifier.

In this embodiment, the reference voltage V_(REF) is input to thenon-inverting input terminal of the buffer amplifier, that is, the gateof MN2 is used as the non-inverting input terminal and the referencevoltage V_(REF) is input thereto; the inverting input terminal isconnected to the output terminal to form a negative feedback, that is,the gate of MN1 is used as the inverting input terminal and is connectedto the drain of MN2 used as the output terminal of the differential unitto form a negative feedback, to stabilize the output voltage V_(OUT) ofthe buffer amplifier.

When the buffer amplifier is operating, the voltages at the invertinginput terminal and the non-inverting input terminal are both greaterthan a threshold voltage V_(TH), such that MN1 and MN2 are conducted,and the buffer amplifier normally operates. In this case, the outputvoltage V_(OUT) of the buffer amplifier is:V _(OUT) =V _(REF) −V _(OS)  (1)V _(OS) =V _(GSMN1) −V _(GSMN2)  (2)

V_(OUT) is the output voltage of the buffer amplifier, V_(OS) is theoffset voltage of the buffer amplifier, V_(REF) is the input referencevoltage, V_(GSMN1) is the voltage between the source S of MN1 and thegate G of MN1, and V_(GSMN2) is the voltage between the source S of MN2and the gate G of MN2.

In practice, the differential input pair transistors of the bufferamplifier do not match, such that V_(GSMN1) and V_(GSMN2) are not equal;and when the input voltage is 0 V, the output voltage is not 0 V. As aresult, the offset voltage V_(OS) is not 0 V.

FIG. 4 is a schematic structural diagram of another operationalamplifier according to an embodiment of the present disclosure. Asillustrated in FIG. 4, different from the above embodiment, in thisembodiment, the operational amplifier is specifically a flipped voltagefollower (FVF). The FVF includes: PMOS transistors MP4 and MP5, an NMOStransistor MN5, and bias current sources Ibias1 and Ibias2.

A drain of MP4 is connected to the drive voltage VDD, a source of MP4 isconnected to a drain of MP5, a gate of MP4 is connected to a drain ofMN5, a drain of MN5 is connected to the drive voltage VDD via the biascurrent source Ibias1, and a source of MN5 is connected to a source ofMP5 and connected to the ground via the bias current source Ibias2. MN5and MP5 are the differential input pair transistors of the operationalamplifier, gates of MN5 and MP5 are respectively used as the invertinginput terminal and the non-inverting input terminal of the operationalamplifier, and the drain of MP5 is used as the output terminal of theoperational amplifier.

The above MP4, MP5, MN5, Ibias1 and Ibias2, and the specific connectionstherebetween form the FVF.

In this embodiment, the non-inverting input terminal and the invertinginput terminal of the operational amplifier are both connected to thereference voltage V_(REF), the output terminal of the operationalamplifier is connected to MN5 via a source and a drain of MP4 to form anegative feedback to stabilize the output voltage V_(OUT).

When the operational amplifier is operating, the reference voltageV_(REF) is simultaneously input to the inverting input terminal and thenon-inverting input terminal, and V_(REF) is greater than the thresholdvoltage V_(TH) of MN5 and MP5, such that MN5 and MP5 are conducted andthe operational amplifier normally operates. In this case, the outputvoltage V_(OUT) of the operational amplifier is:V _(OUT) =V _(REF) −V _(GSMP5)  (3)

V_(GSMP5) is the offset voltage V_(OS) of the FVF.

Optionally, based on the above operational amplifier, the voltageregulator may include a control switch, configured to be connected tothe output terminal of the operational amplifier and an electronicsystem, for example, a control switch as illustrated in FIG. 4, or acontrol switch 404 as illustrated in FIG. 4. The control switch isturned on when the electronic system is in a standby working mode, suchthat the output voltage of the operational amplifier supplies power fora part of modules in the standby electronic system to ensure normaloperation of the electronic system.

It should be noted that FIG. 3 and FIG. 4 only describes the operationalamplifier using the specific circuit structures. However, these circuitstructures are not intended to limit the operational amplifier in thepresent disclosure, but other circuit structures may also be used. Inpractice, for persons of ordinary skill in the art, other types ofoperational amplifiers may also be employed, or operational amplifiersdeveloped by optimizing and improving the structure as illustrated inFIG. 3 or FIG. 4 may be employed.

FIG. 5 is a schematic structural diagram of an offset voltage controlmodule according to an embodiment of the present disclosure. In thisembodiment, description is given using the offset voltage control moduleused in the buffer amplifier in FIG. 3 as an example. In thisembodiment, as illustrated in FIG. 5, the offset voltage control moduleincludes:

eight stages of regulation branches connected in parallel; where eachstage of regulation branch includes a regulation element and aregulation switch. The regulation branch is connected to a deviceaffecting the offset voltage V_(OS) inside the operational amplifier(for example, the regulation branch may be connected to MN1 and MN2 inthe operational amplifier in FIG. 3). Specifically, with respect to anystage of regulation branch, conduction of the regulation branch iscontrolled by controlling conduction of the regulation switch, such thatthe regulation element of the conducted regulation branch is connectedto the operational amplifier to control the offset voltage V_(OS) of theoperational amplifier.

When the offset voltage control module is applied to FIG. 3, the bufferamplifier as illustrated in FIG. 3 includes differential input pairtransistors MN1 and MN2. At least one of the differential input pairtransistors MN1 and MN2 is connected in parallel to any one or morestages of regulation branches in the offset voltage control module, tocontrol a voltage difference between the differential input pairtransistors by the any one or more stages of regulation branches in theoffset voltage control module, and hence to control the offset voltageV_(OS) of the operational amplifier.

In this embodiment, description is given using a scenario where MN2 andany one or more stages of regulation branches in the offset voltagecontrol module are connected in parallel as an example. Since MN2 is anNMOS transistor, the regulation element in the regulation branch in thisembodiment is also an NMOS transistor, the regulation switches on theeight stages of regulation branches are respectively switches 501, 502,503, 504, 505, 506, 507 and 508, and the regulation units arerespectively units MN51, MN52, MN53, MN54, MN55, MN56, MN57 and MN58.

Referring to FIG. 5, the first stage of regulation branch to the eighthstage of regulation branch are illustrated from left to right. Using thefirst stage of regulation branch as an example, description is given tothe structure of the regulation branch.

In the first stage of regulation branch, one terminal of the regulationswitch 501 is connected to a source of the NMNS transistor MN501, andthe other terminal thereof is connected to the source of MN2, that is, anode 509 in FIG. 5 is connected to a node 301 in FIG. 3; a gate of theNMOS transistor MN51, like the gate of MN2, is also connected to thereference voltage V_(REF), and a drain of the NMOS transistor MN51 isconnected to the drain of MN2, that is, a node 510 in FIG. 5 isconnected to a node 302 in FIG. 3; when the regulation switch 501 isturned on, the NMOS transistor MN51 shares a common source, gate anddrain with MN2, such that MN2 and the NMOS transistor MN51 are connectedin parallel to be equivalent to a new NMOS transistor MN2′.

According to the features of the MOS transistor, the equivalent MN2′ hasan increased or decreased width-to-length ratio relative to MN2. Forexample, MN2 and the NMOS transistor MN51 both have a width of W1, alength of L1 and a width-to-length ratio of W1/L1, and in this case, theNMOS transistor MN51, sharing the common source, gate and drain withMN2, is equivalent to MN2′, MN2′ has a width of 2W1, a length of L1 anda width-to-length ratio of 2W1/L1, the width-to-length ratio of theequivalent MN2′ is twice the width-to-length ratio of MN2; or MN2 has awidth of W1, a length of L1 and a width-to-length ratio of W1/L1, theNMOS transistor MN51 has a width of W1, a length of ½L1 and awidth-to-length ratio of W1/½L1, and in this case, the NMOS transistorMN51, sharing the common source, gate and drain with MN2, is equivalentto MN2′, MN2′ has a width-to-length ratio of W1/2L1, and thewidth-to-length ratio of the equivalent MN2′ is ½ of the width-to-lengthratio of MN2.

The NMOS transistor further has the following basic features:

$\begin{matrix}{V_{GS} = {V_{TH} + \sqrt{\frac{2 \star I_{D}}{\mu\;{C\left( {W/L} \right)}}}}} & (4)\end{matrix}$

V_(GS) is the voltage between the gate G and the source S of the NMOStransistor, I_(D) is the current of the drain D of the NMOS transistor,V_(TH) is the starting voltage of the NMOS transistor, μ is the impurityconcentration of the NMOS transistor, C is the capacitance of anoxidation layer of the NMOS transistor, W is the channel width of theNMOS transistor, L is the channel length of the NMOS transistor, and W/Lis the width-to-length ratio of the NMOS transistor.

As seen from formula (4), when I_(D) of the NMOS transistor does notchange but W/L changes, V_(GS) may change with the change of W/L. Inthis case, in this embodiment, the width-to-length ratio of the NMOStransistor connected in parallel to MN2 may be controlled by controllingconduction and non-conduction of the regulation switch, such that thewidth-to-length ratio of the equivalent MN2′ is controlled, and thusV_(GS) of the equivalent MN2′ is controlled. As known from the bufferamplifier in FIG. 2, and formula (1) and formula (2), when V_(GS) (thatis, V_(GMSN2) in the formulae) of MN2′ changes, the offset voltageV_(GS) may correspondingly change, such that the output voltage V_(OUT)of the operational amplifier change likewise. Specifically, in formula(1) and formula (2), when V_(GSMN2) increases, the offset voltage V_(OS)decreases and the output voltage V_(OUT) increases; and on the contrary,the output voltage V_(OUT) decreases.

Preferably, in this embodiment, when the offset voltage control moduleincludes more stages of regulation branches, the width-to-length ratiosof the MOS transistors in different regulation branches may be definedbased on a predefined rule, to control a variation trend of the offsetvoltage V_(OS). For example, in the eight regulation branches, thewidth-to-length ratios of the MOS transistors in the regulation branchesascend from left to right, in regulation of the offset voltage, theregulation switches are controlled to be turned on sequentially fromleft to right, the width-to-length ratio of the NMOS transistorconnected in parallel to MN2 increases, and as a result, the change ofthe width is greater than the change of the length upon the equivalenteffect such that the width-to-length ratio of the equivalent MN2′increases, and thus the offset voltage V_(OS) increases progressively;and on the contrary, the regulation switches are controlled to be turnedon sequentially from right to left, the width-to-length ratio of theNMOS transistor connected in parallel to MN2 decreases, and as a result,the change of the width is smaller than the change of the length uponthe equivalent effect, such that the width-to-length ratio of theequivalent MN2′ decreases, and thus the offset voltage V_(OS) decreasesprogressively.

Specifically, the width-to-length ratios of the MOS transistors indifferent regulation branches are defined to increase progressivelybased on a predefined step, to control the offset voltage V_(OS) tochange linearly. For example, in the eight regulation branches, fromleft to right, the width-to-length ratios of the MOS transistors in theregulation branches are defined to increase progressively based on thepredefined step, in regulation of the offset voltage V_(OS), theregulation switches are initially turned off and turned on where theoffset voltage V_(OS) needs to be regulated, the regulation switches areturned on sequentially from left to right, and only one regulationswitch is turned on each time, such that the width-to-length ratio ofthe equivalent MN2′ increases likewise based on a specific step by theMOS transistors whose width-to-length ratios are defined to increaseprogressively based on the predefined step in the regulation branches.In this way, V_(GS) of the equivalent MN2′ decreases progressively andlinearly. As seen from formula (1) and formula (2), when V_(GS) (thatis, V_(GSMN2) in the formulae) of MN2′ decreases progressively andlinearly, the offset voltage VOS increases progressively and linearly.On the contrary, the regulation switches are initially turned off andturned on where the offset voltage V_(OS) needs to be regulated, theregulation switches are turned on sequentially from right to left, andonly one regulation switch is turned on each time, such that thewidth-to-length ratio of the equivalent MN2′ increases likewise based ona specific step by the MOS transistors whose width-to-length ratios aredefined to increase progressively based on the predefined step in theregulation branches. In this way, V_(GS) of the equivalent MN2′increases progressively and linearly. As seen from formula (1) andformula (2), when V_(GS) (that is, V_(GSMN2) in the formulae) of MN2′increases progressively and linearly, the offset voltage V_(OS)decreases progressively and linearly. Only one regulation switch isturned on each time. This may reduce the number of conducted regulationbranches, such that the change of the offset voltage VOS is morecontrollable. Nevertheless, in other practice of this embodiment, moreregulation switches may be simultaneously turned on.

When the regulation switches in all stages of regulation branches in theoffset voltage control module are turned off, no regulation branch inthe offset voltage control module is connected to the operationalamplifier. In this case, the offset voltage control module is notconnected to the operational amplifier any longer. Under thiscircumstance, if the buffer amplifier in FIG. 3 is an ideal amplifier,that is, MN1 well matches MN2, the offset voltage V_(OS) is 0 V.

Nevertheless, settings of the width-to-length ratios of the MOStransistors in the regulation branches are only exemplarily describedhereinabove, and the specific values may be determined based on othermethods, for example, software simulation and the like.

In this embodiment, the values of the width-to-length ratios of the MOStransistors in the regulation branches may be further defined, such thata change range of the offset voltage V_(OS) is (−M, M). When theregulation switches are all turned off, the offset voltage V_(OS) is 0V. In this case, the output voltage V_(OUT) is equal to V_(REF), suchthat a drive capability may be increased for the reference voltageV_(REF) to obtain a voltage V_(OUT) having the drive capability. Whenthe eighth stage of regulation switch is turned off, the offset voltageV_(OS) is M V. In this case, the output voltage V_(OUT) is equal toV_(REF)−V_(OS)=V_(REF)−M, such that a buck output similar to buck-typeDC-DC. When the first stage of regulation switch is turned off, theoffset voltage V_(OS) is −M V. In this case, the output voltage V_(OUT)is equal to V_(REF)−V_(OS)=V_(REF)+M, such that a boost output similarto boost-type DC-DC.

Nevertheless, in this embodiment, the offset voltage control module isexemplarily described using a scenario where the eight stages ofregulation branches are connected in parallel to MN2 in FIG. 3 as anexample. In other practice of the present application, the offsetvoltage control module may also be connected to MN1 in parallel, or twooffset voltage control modules may be arranged. Each offset voltagecontrol module includes eight stages of regulation branches. The two 8stages of regulation branches are respectively connected to MN1 and MN2in parallel. The number of stages of regulation branches connected inparallel is not limited to 8, and the specific number of stages may beadaptively modified. For example, when 10 different voltage values needto be output with respect to the output voltage V_(OUT) of theoperational amplifier, nine stages of regulation branches may bearranged. The operational amplifier may also be modified. For example,the offset voltage control module in FIG. 5 may likewise be connected inparallel to MP5 in FIG. 4.

In other practice of the present disclosure, the differential input pairtransistors and the transistors in the regulation branches may beadaptively replaced according to the actual needs. For example, the NMOStransistors may be replaced by PMOS transistors. The solutions upon suchreplacements shall also fall within the protection scope of the presentdisclosure, which are not described herein any further.

In addition, based on the above embodiments, the reference voltageirrelevant to the temperature coefficient in the voltage regulator isspecifically generated by the bandgap reference generation circuit.

The bandgap reference generation circuit uses a sum of a voltagenegatively proportional to the temperature and a voltage positivelyproportional to the temperature, such that the temperature coefficientsof these two voltages are offset, such that a circuit of the referencevoltage irrelevant to the temperature is obtained.

FIG. 6 is a schematic structural diagram of a conventional bandgapreference generation circuit according to an embodiment of the presentdisclosure. As illustrated in FIG. 6, the bandgap reference generationcircuit includes: an operational amplifier (OPA), PMOS transistors MP61,MP62 and MP63, BJT transistors BJT61 and BJT62, resistors R2A, R2B, R3and R4, where R2A=R2B.

Drains of MP61, MP62 and MP63 are connected to the drive voltage VDD,gates thereof are connected to an output terminal of the OPA; the drainof MP61 is connected to a non-inverting input terminal of the OPA,connected to the ground via the resistor R2B and connected to an emitterof BJT61 via the resistor R3; the drain of MP62 is connected to aninverting input terminal of the OPA, connected to the ground via theresistor R2A and connected to an emitter of BJT62; a base of BJT61 isconnected to a base of BJT62 and connected to the ground; a collector ofBJT61 and a collector of BJT62 are connected to the ground; a ratio ofthe area of the emitter of BJT61 to the area of the emitter of BJT62 isN:1; the drain of MP63 is connected to the ground via the resistor R4,and the drain of MP63 is configured to output a single-fold bandgapreference voltage V_(REF):

$\begin{matrix}{V_{REF} = {\frac{R_{4}}{R_{2\; A}}\left\lbrack {{U_{T}\frac{R_{2\; A}}{R_{3}}{\ln(N)}} + V_{{EB}\; 61}} \right\rbrack}} & (5)\end{matrix}$

U_(T) is a thermal voltage, and V_(EB61) is a voltage between a base Band the collector E of BJ61. A reference voltage irrelevant to thetemperature may be obtained by regulating a ratio of the resistor R2A tothe resistor R3. Regulating the ratio of the resistor R4 to the resistorR2A may change the value of V_(REF).

In this embodiment, to further reduce power consumption, the bandgapreference generation circuit may be one of: a ΔV_(GS)-based (V_(GS) is avoltage between the gate and the source of a MOS transistor) bandgapreference generation circuit having a full CMOS reference offsetstructure, a proportional to absolute temperature (PTAT) unit-based andV_(GS)-based bandgap reference generation circuit having a full CMOSreference offset structure, and a PTAT unit-based and bipolar junctiontransistor (BJT)-based bandgap reference generation circuit having acomplementary structure. These three circuits are all CMOS-basedcircuits, and therefore, has less power consumption and a small area.

For example, the PTAT unit-based and BJT-based bandgap referencegeneration circuit having a complementary structure specificallyincludes:

a BJT transistor, configured to generate a voltage having a positivetemperature coefficient based on a voltage between a base and an emitterof the BJT transistor; and

a MOS transistor-based PTAT unit, configured to generate a voltagehaving a negative temperature coefficient based on a MOS transistoroperating in a subthreshold region;

where the emitter of the BJT transistor and the PTAT unit are connectedto a drive voltage VDD via a current unit, such that the BJT transistorand the PTAT unit have a predefined offset current such that the voltagehaving the positive temperature coefficient and the voltage having thenegative temperature coefficient are complementary to each other and thereference voltage irrelevant to the temperature coefficient isgenerated.

A single-fold bandgap reference voltage V_(REF1) is typically 1.2 V. Toobtain an n-fold bandgap reference voltage, in this embodiment, the PTATunit-based and BJT-based bandgap reference generation circuit having acomplementary structure includes n groups of PTAT units and n BJTtransistors. The voltage having the positive temperature coefficientgenerated by each BJT transistor is complementary to the voltage havingthe negative temperature coefficient generated by each group of PTATunits, such that the generated reference voltage is the n-fold bandgapreference voltage.

Specifically, when n is equal to 2, a structure of the PTAT unit-basedand BJT-based bandgap reference generation circuit having acomplementary structure is as illustrated in FIG. 7. In FIG. 7, thecurrent unit may be specifically a current mirror which includes:

BJT transistors B1 and B2; where an emitter of the BJT transistor B1 isconnected to the drive voltage VDD via a current mirror, a base of theBJT transistor B1 is connected to a collector thereof, and the collectoris connected to the ground; an emitter of the BJT transistor B2 isconnected to the drive voltage VDD via the current mirror, and ancollector of the BJT transistor B2 is connected to the ground, such thatthe voltage having the positive temperature coefficient is generatedbased on the voltage between the base and the emitter of the BJTtransistor; and

two groups of MOS transistor-based PTAT units, configured to generate avoltage having a negative temperature coefficient based on a MOStransistor operating in a subthreshold region; where the PTAT unitsinclude two groups and totally eight stages, with four stages includedin each group, and the two groups of PTAT units are arranged in seriesbetween the emitter of B1 and the base of B2;

where the emitter of the BJT transistor and the PTAT unit are connectedto a drive voltage VDD via a current mirror, such that the BJTtransistor and the PTAT unit have a predefined offset current such thatthe voltage having the positive temperature coefficient and the voltagehaving the negative temperature coefficient are complementary to eachother and the reference voltage irrelevant to the temperaturecoefficient is generated.

A node between the two groups of PTAT units is a single-fold bandgapoutput node, configured to output a single-fold bandgap referencevoltage, that is, a 1.2 V reference voltage V_(REF1), the emitter of thesecond BJT transistor is a double-fold bandgap output node, configuredto output a double-fold bandgap reference voltage V_(REF2), that is, a2.5 V reference voltage. In this way, the single-fold bandgap referencevoltage and the double-fold bandgap reference voltage may besimultaneously obtained.

Specifically, as illustrated in FIG. 8, the PTAT unit includes two NMOStransistors MNA and MNB. A source of MNA is connected to the ground, agate of MNA is connected to a gate of MNB and a drain of MNB, and thedrain of MNB is connected to the drive voltage VDD via the currentmirror. The current mirror may ensure that bias currents I_(B) ofvarious PTAT units are equal (that is, the above predefined biascurrent). The two NMOS transistors of the PTAT unit both operate in asubthreshold region. As known from a long channel static model, whendrain and source voltages of the NMOS transistor are greater than 4-5U_(T), the NMOS transistor operates in a positive phase saturatedregion. Drain and source currents in the positive phase saturated regionare as follows:I _(D) =I _(S) ·e ^([−V) ^(T0) ^(/nU) ^(T) ^(]) ·e ^([V) ^(G) ^(/nU)^(T) ^(])·[e ^((−V) ^(S) ^(/U) ^(T) ⁾ −e ^((−V) ^(D) ^(/U) ^(T) ⁾]  (6)I _(S)=2*(W/L),U _(T) ² I _(S)=2·n·(W/L)·U _(T) ²  (7)

U_(T) is a thermal voltage of the NMOS transistor, V_(T0) is anintrinsic threshold voltage of the NMOS transistor, and n is aweak-inversion slope factor.

In addition, the transistor MNB operates in the positive phase saturatedregion further satisfies V_(D)−V_(S)≥U_(T), and in this case, a voltageto ground V_(O) at the drain of the transistor MNA is:

$\begin{matrix}{V_{O} = {U_{T} \cdot {\ln\left\lbrack {1 + {\frac{S_{TB}}{S_{TA}} \cdot \frac{I_{DTA}}{I_{DTB}}}} \right\rbrack}}} & (8)\end{matrix}$

S_(TA) is a dimension of the transistor MNA, S_(TB) is a dimension ofthe transistor MNB, I_(DTA) is a drain current of the transistor MNA,and I_(DTB) is a drain current of the transistor MNB.

Input and output nodes of the PTAT unit are respectively nodescorresponding to the ground point and the drain of the transistor MNA inFIG. 8. When the PTAT units are connected in series to form a bandgapreference generation circuit, as illustrated in FIG. 7, a input node ofthe PTAT unit is connected to the output node of a previous stage ofPTAT unit, and the output node of a PTAT unit is connected to the inputnode of a next stage of PTAT unit. The input node of the first stage ofPTAT unit (that is, the PTAT unit on the leftmost side in FIG. 7) isconnected to the emitter of B1. When a PTAT unit is the last stage ofPTAT unit (that is, the PTAT unit on the rightmost side in FIG. 7), theoutput node is connected to the base of B2.

Specifically, for ease of calculation, herein it is assumed thatparameters of B1 and B2 are totally the same, and parameters of all thePTAT units are also totally the same. Based on the above PTAT unit,current input terminals of a current mirror unit may be MP71, andMP72-MP79, and MP813 is a mirror unit whose gate is connected to a biasvoltage VBP such that the mirror unit operates. In FIG. 7, MN71 and MN72 are the first stage of PTAT units, MN73 and MN74 are the second stageof PTAT units, and analogously, MN715 and MN716 are the eighth stage ofPTAT units. B1 and B2 are respectively connected to the drive voltageVDD via MP 71 and MP713. The eight stages of PTAT units are respectivelyconnected to the drive voltage VDD via MP72-MP79. In this case, asingle-fold bandgap output node 701 in FIG. 7 output a single-foldbandgap reference voltage V_(REF1) as follows:V _(REF1) =V _(BE)+Σ_(N=5) ⁸ U _(T)·ln(1+β·α)  (9)

In FIG. 7, a double-fold bandgap output node 702 outputs a double-foldbandgap reference voltage V_(REF2) as follows:V _(REF2)=2V _(BE)+Σ_(N=1) ⁸ U _(T)·ln(1+β·α)  (10)

In the above formulae, α=S₁/S₂=S₃/S₄= . . . =S₁₅/S₁₆, S₁-S1 ₆ arerespectively dimensions of the NMOS transistors MN71, MN72, MN73, MN74,MN75, MN76, MN77, MN78, MN79, MN710, MN711, MN712, MN713, MN714, MN715and MN716 in the eight stages of PTAT units in FIG. 1,β=I_(D1)/I_(D2)=I_(D3)/I_(D4)= . . . =I_(D15)/I_(D16), I_(D1)-I_(D16)are respectively the drain currents of the NMOS transistors MN71, MN72,MN73, MN74, MN75, MN76, MN77, MN78, MN79, MN710, MN711, MN712, MN713,MN714, MN715 and MN716 in the eight stages of PTAT units in FIG. 1, andV_(BE) is a voltage between the bases B and the collectors E of B1 andB2, and N is the number of stages of the PTAT units.

Optionally, in this embodiment, the PTAT unit-based and BJT-basedbandgap reference generation circuit having a complementary structurefurther includes a reference voltage control switch. One terminal of thereference voltage control switch is connected to the drive voltage VDDvia a current unit, and the other terminal of the reference voltagecontrol switch is connected to the PTAT unit, to control a currentflowing through the PTAT unit based on conduction and non-conduction ofthe reference voltage control switch, and hence to control a value ofthe reference voltage and a temperature coefficient of the referencevoltage.

As illustrated in FIG. 7, MP710, MP711 and MP712 are the same asMP72-MP79, and are all mirror units of the current mirror; one terminalof each of reference voltage control switches 703, 704 and 705 isconnected to a node 106 (that is, the output node of the last stage ofPTAT unit), and the other terminal of each of reference voltage controlswitches 703, 704 and 705 is connected to the drive voltage VDDrespectively via MP710, MP711 and MP712 of the current mirror. Bycontrolling conduction and non-conduction of the reference voltagecontrol switches 703, 704 and 715, the current of the PTAT units may beincreased, that is, I_(DTA) in formula (7) may be increased, such thatV_(O) in formula (7) is increased. In this way, by controlling the valueof V_(O), the value of the reference voltage and the temperaturecoefficient of the reference voltage may be controlled.

The 1.2 V single-fold bandgap reference voltage and the 2.5 Vdouble-fold bandgap reference voltage generated by the =PTAT unit-basedand BJT-based bandgap reference generation circuit having acomplementary structure, and the bias currents output by the single-foldbandgap output node 701 and the double-fold bandgap output node 702 areall small, such that the reference voltage V_(REF) is only sufficient tobe connected to a capacitive load, without a current load capability.However, in practice, the output reference voltage V_(REF) does not needto be connected to the capacitive load, but needs to supply power for ananalog circuit.

Hereinafter, increasing the current load capacity to the bandgapreference generation circuit is described using a specific applicationscenario. The bandgap reference generation circuit in FIG. 7 maygenerate a single-fold bandgap reference voltage V_(REF1) of 1.2 V, andgenerate a double-fold bandgap reference voltage V_(REF2) of 2.5 V. Inpractice, the single-fold bandgap reference voltage V_(REF1) and thedouble-fold bandgap reference voltage V_(REF2) all need to supply powerfor an electronic system in a standby state. The single-fold bandgapreference voltage V_(REF1) may be used to supply power for a capacitiveload of the electronic system, and thus the current load capability isnot needed. The single-fold bandgap reference voltage V_(REF2) may beused to supply power for an analogy circuit, and thus the current loadcapability is needed. However, the double-fold bandgap reference voltageV_(REF2) output in FIG. 2 has a small bias current which is only 4 nA.If the electronic system extracts the bias current such that the circuithas the current load capability, the entire bandgap reference generationcircuit may fail to operate. In this case, the double-fold bandgapreference voltage V_(REF2) may be input to the buffer amplifier in FIG.3, such that the current load capability is increased for thedouble-fold bandgap reference voltage V_(REF2) to enable the double-foldbandgap reference voltage V_(REF2) to supply power for the analogcircuit. After the buffer amplifier in FIG. 3 is connected, the loadcurrent may be maximally 1 mA, and in the meantime, the value of theoutput voltage V_(OUT) may be regulated by the offset voltage controlmodule connected to the buffer amplifier. In addition, the bufferamplifier may also achieve an isolation effect. That is, the bufferamplifier may prevent signals in the connected analog circuit fromcausing interference to the bandgap reference generation circuit.

Nevertheless, in other application scenarios, the single-fold bandgapreference voltage V_(REF1) may also be input to an operationalamplifier, for example, the FVF in FIG. 4, such that the value of theoutput voltage V_(OUT) is increased by the FVF and thus a high outputvoltage V_(OUT) is obtained, and the value of the output voltage V_(OUT)is regulated by the offset voltage control module connected to the FVFin FIG. 4.

Another embodiment of the present application further provides a powersupply. The power supply includes the above described voltage regulator.

In this embodiment, sine each stage of regulation branch in the offsetvoltage control module in the voltage regulator is based on a transistorstructure, as compared with the voltage dividing resistor in the relatedart, the transistor has lower power consumption, and thus powerconsumption of the power supply is lowered.

In addition, a person skilled in the art should understand the abovedivision of units and modules is only an exemplary one, and if theapparatus is divided into other units or modules or not divided, thetechnical solution shall also fall within the protection scope of thepresent application as long as the information object has the abovefunctions.

A person skilled in the art shall understand that the embodiments of thepresent application may be described to illustrate methods, apparatuses(devices), or computer program products. Therefore, hardwareembodiments, software embodiments, or hardware-plus-software embodimentsmay be used to illustrate the present application. In addition, thepresent application may further employ a computer program product whichmay be implemented by at least one non-transitory computer-readablestorage medium with an executable program code stored thereon. Thenon-transitory computer-readable storage medium comprises but notlimited to a disk memory, a CD-ROM, and an optical memory.

Embodiments of the present disclosure are described based on theflowcharts and/or block diagrams of the method, apparatus (device), andcomputer program product. It should be understood that each processand/or block in the flowcharts and/or block diagrams, and anycombination of the processes and/or blocks in the flowcharts and/orblock diagrams may be implemented using computer program instructions.These computer program instructions may be issued to a computer, adedicated computer, an embedded processor, or processors of otherprogrammable data processing device to generate a machine, which enablesthe computer or the processors of other programmable data processingdevices to execute the instructions to implement an apparatus forimplementing specific functions in at least one process in theflowcharts and/or at least one block in the block diagrams. Thesecomputer program instructions may also be stored a non-transitorycomputer-readable memory capable of causing a computer or otherprogrammable data processing devices to work in a specific mode, suchthat the instructions stored on the non-transitory computer-readablememory implement a product comprising an instruction apparatus, wherethe instruction apparatus implements specific functions in at least oneprocess in the flowcharts and/or at least one block in the blockdiagrams.

These computer program instructions may also be stored on a computer orother programmable data processing devices, such that the computer orthe other programmable data processing devices execute a series ofoperations or steps to implement processing of the computer. In thisway, the instructions, when executed on the computer or the otherprogrammable data processing devices, implement the specific functionsin at least one process in the flowcharts and/or at least one block inthe block diagrams.

Although the preferred embodiments of the present application aredescribed above, once knowing the basic creative concept, a personskilled in the art can make other modifications and variations to theseembodiments. Therefore, the appended claims are intended to be construedas covering the preferred embodiments and all the modifications andvariations falling within the scope of the present application.Obviously, a person skilled in the art can make various modificationsand variations to the present application without departing from thespirit and scope of the present application. In this way, the presentapplication is intended to cover the modifications and variations ifthey fall within the scope of the appended claims of the presentapplication and equivalent technologies thereof.

What is claimed is:
 1. A voltage regulator, comprising: an operationalamplifier including an input terminal and an output terminal, and theoperational amplifier is configured to generate an output voltage to beoutput from the output terminal based on a reference voltage receivedfrom the input terminal; and an offset voltage control module includingone stage of regulation branch or more stages of regulation branchesconnected in parallel, and the offset voltage control module isconfigured to control an offset voltage of the operational amplifierbased on selection of the regulation branch to regulate the outputvoltage, wherein the one stage of regulation branch or each of the morestages of regulation branches comprises a regulation element and aregulation switch, and the regulation branch is connected to a deviceaffecting the offset voltage inside the operational amplifier; whereinconduction of the regulation branch is controlled by controllingconduction of the regulation switch, such that the regulation element ofthe conducted regulation branch is connected to the operationalamplifier to control the offset voltage of the operational amplifier. 2.The voltage regulator according to claim 1, wherein the regulationelement is a MOS transistor.
 3. The voltage regulator according to claim2, wherein when the offset voltage control module comprises more stagesof regulation branches, width-to-length ratios of MOS transistors ofdifferent regulation branches are defined based on a predetermined ruleto control a variation trend of the offset voltage.
 4. The voltageregulator according to claim 3, wherein the width-to-length ratios ofthe MOS transistors of the different regulation branches are defined inan ascending order based on a predetermined step to control the offsetvoltage to be subject to a linear variation.
 5. The voltage regulatoraccording to claim 1, wherein when the regulation switches in all stagesof regulation branches in the offset voltage control module are allturned off, the offset voltage is 0 V.
 6. The voltage regulatoraccording to claim 1, wherein the operational amplifier comprises adifferential input pair transistors; wherein at least one of thedifferential input pair transistors is connected in parallel to any oneor more stages of regulation branches in the offset voltage controlmodule to control a voltage difference between the differential inputpair transistors by the any one or more stages of regulation branches inthe offset voltage control module, and hence to control the offsetvoltage of the operational amplifier.
 7. The voltage regulator accordingto claim 1, further comprising a bandgap reference generation circuit,configured to generate a reference voltage irrelevant to a temperaturecoefficient.
 8. The voltage regulator according to claim 7, wherein thebandgap reference generation circuit comprises at least one of: aΔV_(GS)-based bandgap reference generation circuit having a full CMOSreference offset structure, a PTAT unit-based and V_(GS)-based bandgapreference generation circuit having a full CMOS reference offsetstructure, and a PTAT unit-based and BJT-based bandgap referencegeneration circuit having a complementary structure.
 9. The voltageregulator according to claim 8, wherein the PTAT unit-based andBJT-based bandgap reference generation circuit having a complementarystructure comprises: a BJT transistor, configured to generate a voltagehaving a positive temperature coefficient based on a voltage between abase and an emitter of the BJT transistor; and a MOS transistor-basedPTAT unit, configured to generate a voltage having a negativetemperature coefficient based on a MOS transistor operating in asubthreshold region; wherein the emitter of the BJT transistor and thePTAT unit are connected to a drive voltage via a current unit, such thatthe BJT transistor and the PTAT unit have a predefined offset currentsuch that the voltage having the positive temperature coefficient andthe voltage having the negative temperature coefficient arecomplementary to each other and the reference voltage irrelevant to thetemperature coefficient is generated.
 10. The voltage regulatoraccording to claim 9, wherein the PTAT unit-based and BJT-based bandgapreference generation circuit having a complementary structure comprises:n groups of PTAT units and n BJT transistors, wherein the voltage havingthe positive temperature coefficient generated by each BJT transistor iscomplementary to the voltage having the negative temperature coefficientgenerated by each group of PTAT units, such that the generated referencevoltage is an n-fold bandgap reference voltage.
 11. The voltageregulator according to claim 10, wherein when n is equal to 2, the PTATunit-based and BJT-based bandgap reference generation circuit having acomplementary structure comprises: BJT transistors B1 and B2; wherein anemitter of the BJT transistor B1 is connected to the drive voltage via acurrent mirror, a base of the BJT transistor B1 is connected to acollector thereof, and the collector is connected to the ground; anemitter of the BJT transistor B2 is connected to the drive voltage viathe current mirror, and an collector of the BJT transistor B2 isconnected to the ground, such that the voltage having the positivetemperature coefficient is generated based on the voltage between thebase and the emitter of the BJT transistor; and two groups of MOStransistor-based PTAT units; wherein the two groups of PTAT units arearranged in series between the emitter of the BJT transistor B1 and thebase of the BJT transistor B2, a node between the two groups of PTATunits is a single-fold bandgap output node configured to output asingle-fold bandgap reference voltage, and the emitter of the BJTtransistor B2 is a double-fold bandgap output node configured to outputa double bandgap reference voltage.
 12. The voltage regulator accordingto claim 9, wherein the bandgap reference generation circuit furthercomprises a reference voltage control switch; wherein one terminal ofthe reference voltage control switch is connected to the drive voltagevia the current unit, and the other terminal of the reference voltagecontrol switch is connected to the PTAT unit to control a currentflowing through the PTAT unit based on conduction and non-conduction ofthe reference voltage control switch, and hence to control a value ofthe reference voltage and a temperature coefficient of the referencevoltage.
 13. The voltage regulator according to claim 9, wherein thecurrent unit is a current mirror.
 14. The voltage regulator according toclaim 1, further comprising a control switch, configured to be connectedto the output terminal of the operational amplifier and an electronicsystem, wherein the control switch is turned on when the control switchis in standby such that the output voltage of the operational amplifiersupplies power for a part of modules in the standby electronic system.15. The voltage regulator according to claim 1, wherein the operationalamplifier comprises a buffer amplifier.
 16. A power supply, comprising avoltage regulator, wherein the voltage regulator comprises: anoperational amplifier including an input terminal and an outputterminal, and the operational amplifier is configured to generate anoutput voltage to be output from the output terminal based on areference voltage received from the input terminal; and an offsetvoltage control module including one stage of regulation branch or morestages of regulation branches connected in parallel, and the offsetvoltage control module is configured to control an offset voltage of theoperational amplifier based on selection of the regulation branch toregulate the output voltage, wherein the one stage of regulation branchor each of the more stages of regulation branches comprises a regulationelement and a regulation switch, and the regulation branch is connectedto a device affecting the offset voltage inside the operationalamplifier; wherein conduction of the regulation branch is controlled bycontrolling conduction of the regulation switch, such that theregulation element of the conducted regulation branch is connected tothe operational amplifier to control the offset voltage of theoperational amplifier.
 17. A voltage regulator, comprising: anoperational amplifier including an input terminal and an outputterminal, and the operational amplifier is configured to generate anoutput voltage to be output from the output terminal based on areference voltage received from the input terminal; and an offsetvoltage control module including one stage of regulation branch or morestages of regulation branches connected in parallel, and the offsetvoltage control module is configured to control an offset voltage of theoperational amplifier based on selection of the regulation branch toregulate the output voltage, wherein the operational amplifier comprisesa differential input pair transistors; wherein at least one of thedifferential input pair transistors is connected in parallel to any oneor more stages of regulation branches in the offset voltage controlmodule to control a voltage difference between the differential inputpair transistors by the any one or more stages of regulation branches inthe offset voltage control module, and hence to control the offsetvoltage of the operational amplifier.